The present invention relates to a location control system of a cursor indicator on a screen indicator of an information processing system which includes a computer, a telex terminal, and a word processor. A cursor is used to edit a message and/or a program on a screen.
FIG. 1 shows a conventional cursor control, in which the numeral 1 is a data input with a keyboard, 2 is a message generator, 3 is a message memory for storing a message, 4 is a screen indicator, 4a is a cursor on said screen, 5 is a cursor control for moving said cursor 4a, 5-1 is an up/down control of a cursor, 5-2 is a right/left control of a cursor, and 6 is a message editor for editing a message.
A message is generated by the message generator 2 according to the input by the data input 1, and the message the generated is stored in the message memory 3, and also is indicated on the screen 4.
The input of a message is carried out by using a keyboard on the data input 1. That keyboard has a plurality of keys (alphanumeric keys, and a return key et al).
The message thus generated is indicated on the screen 4 as shown in FIG. 3(a), and said message is stored in the memory 3 as shown in FIG. 3(b). In FIG. 3(a), each line starts at the extreme end on the screen, and the location of the return (carriage return) depends upon each line (B,D,F). On each line of FIG. (a), the right area after the return (B,D,F) symbol is a null area which has no data. So, a screen has a data area and a null area. The memory 3 has no null area in order to save memory cells.
The cursor control 5 moves a cursor on a screen, to edit a message on a screen.
The edition of a message includes correction, deletion, and addition of a character positioned in a data area on a screen, and the destination of a cursor is usually in the data area, but not in null area. The edition in a null area makes no sense, since no message exists in the null area. Therefore, it should be noted that if a cursor moves into a null area, it is transient and is on the way to the data area.
In a conventional manner for locating a cursor, an "up" key and a "down" key in the up/down control 5-1 moves a cursor in a vertical direction on a screen unconditionally, and also a "left" key and a "right" key in the right/left control 5-2 moves unconditionally a cursor in a horizontal direction.
In the example of FIG. 3(a), it is assumed that the cursor locates initially at the position D, and is moved to the position B. In that case, two kinds of operations are possible, as follows.
In a first operation, the cursor at D is first moved to B' just under the position B by using the right/left control 5-2, and then, the cursor is lifted by one line to the position B by using the up/down control 5-1.
In a second operation, the cursor at D is first lifted by one line to B" by using the up/down control 5-1, and then, the cursor is shifted to the position B by depressing the left key of the right/left control 5-2.
Accordingly, it should be noted that both the up/down control 5-1 and the right/left control 5-2 must be operated to move the cursor from D to B. Therefore, the operation of a keyboard is not simple.